交换

Pinyin: jiāohuàn
Meaning：To exchange; to swap
Sentence：他们相互交换了人质。They exchanged hostages with each other.

More:

交：

Pinyin: jiāo
Meaning: Clock
Radical: 亠
Stokes: 6
Traditional: 交
Common words/Phrase:
交谈 [jiāotán] 【talk with each other】
交流 [jiāoliú] 【exchange】
交易 [jiāoyì] 【transaction】
交通 [jiāotōng] 【traffic】
交货 [jiāohuò] 【delivery】

换 ：

Pinyin: huàn
Meaning: change; exchange
Radical: 扌
Stokes: 10
Traditional: 换
Common words/Phrase:
换算 [huànsuàn] 【conversion】
换班 [huànbān] 【shift】
换取 [huànqǔ] 【give something and get something in return】